Magnet links have nothing to do with this... they aren't tracking who downloads a particular .torrent file; they are simply enumerating ALL the peers in a swarm of a particular torrent being "tracked".
In a sense all that really gives people is a somewhat accurate statistic as to how many copies of a particular "copyrighted work" are being downloaded, provided they find and track all the torrents / other means of dissemination.
At this point the "powers that be" know they cannot win the piracy war with the current tools they have on hand, so they study, they learn and eventually will adapt and roll out methods to be able to ferret out individual pirates better and bring them to court.
This is an arms race. They get better at tracking us, and we just get better at hiding. In the previous cases that I have looked at, so far I have not seen the system go after individuals that take measures to protect themselves (using proxies, peer blocks, public WiFi connections, etc.) but that may very well change in the future, or it may not. We shall see.